Regrouping in Subtraction

This is a complete lesson about how to teach regrouping in subtraction (borrowing) step-by-step with 2-digit numbers, meant for 2nd grade. The lesson contains a teaching video, instruction with visual models, and many exercises.

In the video below, I explain an idea of breaking down the concept of regrouping (borrowing) so that students can see what actually happens in it. For example, to subtract 52 − 38, we write 52 as 50 + 2 (breaking it down into its tens and ones). Then, regrouping means that 50 + 2 becomes 40 + 12. This makes the process totally transparent.

We will now study regrouping
(also called "borrowing") in subtraction.

As a first step, we study
breaking
a ten-pillar into ten little cubes.
This is called regrouping,
because one ten "changes
groups" from the tens group
into the ones.

Breaka ten.

4 tens 5 ones

3 tens 15 ones

First we have 45. We
"break" one ten-pillar
into little cubes.

Now we have 3 tens and
15 ones. It is still 45, but
written in a different way.

Here is another example. First
we have 5 tens 3 ones. We
"break" one ten-pillar into
10 little cubes. We end up with
4 tens 13 ones.

Breaka ten.

5 tens 3 ones

4 tens 13 ones

1. Break a ten
into 10 ones. What do you get? Draw or use manipulatives to help.

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